Suspended Matter Concentration Research Articles

Remote Sensing Inversion of the Total Suspended Matter Concentration in the Nanyi Lake Based on Sentinel-3 OLCI Imagery

Remote Sensing Inversion of the Total Suspended Matter Concentration in the Nanyi Lake Based on Sentinel-3 OLCI Imagery

呼伦湖2002–2021年悬浮物浓度数据集

Suspended particular matter (SPM) concentration is one of the parameters in assessing water quality. The monitoring of the long-term variations of suspended particular matter is of great value for lake management and ecological restoration in lake water. As an important lake in the north of China, Hulun Lake is an important part of the "One Lake, Two Seas" initiative. The monitoring of its water quality changes is of great significance to ensuring the ecological security in Northern China. Through the processing of MODIS Aqua data from 2002 to 2021, and by mitigating the impact of water vapor and ozone absorption as well as Rayleigh scattering, we derived Rayleigh-corrected reflectance (Rrc), and subsequently generated the dataset of monthly and yearly mean suspended particulate matter concentration in Hulun Lake spanning the years from 2002 to 2021. The average percentage error of the model was verified to be 16.5%, which can meet the practical needs of long-term observation of the suspended particulate matter in lakes. This dataset can provide theoretical support and practical reference for the monitoring of ecological changes and environmental management of water quality in Hulun Lake.

THE IMPACT OF STILLAGE FILTRATE ON THE SYNTHESIS OF VOLATILE IMPURITIES OF ALCOHOL AND THE OPTIMIZATION OF THE RECTIFICATION PROCESS

The aim of this research is to determine the influence stillage filtrate on the synthesis of volatile impurities in alcohol, with subsequent removal through the rectification process in a rectification unit operating in an energy-saving mode at pressures lower than atmospheric. The study was conducted at the state enterprise (hereinafter - SE) "Kozlivsky Distillery" located at: Ternopil region, Kozlivsky district, urban-type settlement Kozliv, using gas chromatographic method for determining the content of microcomponents (acetaldehyde, methanol, fusel oil components, esters) using capillary columns. The rectification unit includes various components such as the mash column, hydroselection column, rectification column, methanol column, impurity concentration column and "zero" column. During the research, technological parameters of operation of each unit component were studied, and the concentration of organic impurities in alcohol at different stages was determined. The results of this study allow improving the efficiency of the rectification unit, which is of great importance in alcohol production. Research was conducted on the impact stillage filtrate on the synthesis of volatile impurities in alcohol during fermentation. The research was carried out with the full use iltrate of stillage at the stage of preparing the fermenting substrate. The mash had different concentrations of dry substances. The stillage filtrate was obtained by centrifugation of native stillage and its suspended matter concentration did not exceed 1%. The influence of the amount stillage filtrate and the number of cycles of its recirculation on the biosynthesis of volatile organic compounds during fermentation was studied. The research results showed that the use stillage filtrate at the stage of preparing the fermenting substrate contributes to reducing water consumption and slows down the synthesis of acetaldehyde and higher alcohols during fermentation. With repeated use stillage filtrate, the synthesis process changes, which affects the concentration of volatile organic compounds in the fermentation mash. This impact should be taken into account when selecting operating modes of the rectification unit. Therefore, to obtain high-quality rectified alcohol, it is necessary to adjust the appropriate operating mode of the rectification unit and consider the influence stillage filtrate on the fermentation process.

Rainfall-driven resuspension of pathogenic Leptospira in a leptospirosis hotspot

Leptospirosis is a zoonosis caused by Leptospira bacteria present in the urine of mammals. Leptospira is able to survive in soils and can be resuspended during rain events. Here, we analyzed the pathogenic Leptospira concentration as a function of hydrological variables in a leptospirosis hot spot. A total of 226 samples were collected at the outlet of a 3 km2 watershed degraded by ungulate mammals (deer and feral pigs) and rats which are reservoirs for leptospirosis. Water samples collected at the beginning of a rain event following a dry period contained high concentrations of pathogenic Leptospira. The concentration was generally correlated with the water level and the suspended matter concentration (SMC) during the main flood event. A secondary peak of pathogenic Leptospira was sometimes detected after the main flood and in slightly turbid waters. Lastly, the pathogenic Leptospira concentration was extremely high at the end of a wet season. The pathogenic Leptospira concentrations could not be explained by a linear combination of hydrological variables (e.g. the rainfall, water level, SMC and soil moisture). However, nonlinear machine learning models of rainfall data only provided a fair fit to the observations and explained 75 % of the variance in the log10-transformed pathogenic Leptospira concentration. A comparison of identical machine learning models for the water level, SMC and pathogenic Leptospira concentration showed that the residual error in the Leptospira concentration was due to not only the small dataset but also the intrinsic characteristics of the signal. Our results support the hypothesis whereby pathogenic Leptospira survive at different depths in soils and superficial river sediments (depending on their water saturation) and are transferred to surface water during erosion. These results might help to refine leptospirosis warnings given to the local population. Future research should be focused on larger watersheds in more densely populated areas.

Modeling of Suspended Particulate Matter Concentration in an Extremely Turbid River Based on Multispectral Remote Sensing from an Unmanned Aerial Vehicle (UAV)

Following consecutive years of governance efforts, there has been a substantial reduction in sediment transport in the Yellow River, resulting in significant changes in its water–sediment dynamics. This necessitates precise monitoring of sediment-bearing tributary inflows, a crucial requirement for effective governance strategies on the Loess Plateau’s current developmental stage. While satellite remote sensing technology has been widely used to estimate suspended particulate matter concentration (CSPM) in open water bodies like oceans and lakes, its application in narrow rivers presents challenges related to hybrid pixel and proximity effects. As a result, the effectiveness and competence of satellite remote sensing in monitoring CSPM in such confined river environments are reduced. This study attempted to use unmanned aerial vehicle (UAV) remote sensing with multispectral technology to invert CSPM in the Wuding River, a sediment-bearing Yellow River tributary. A novel CSPM concentration inversion model was introduced for highly turbid river settings. The results showed that the accuracy of the new band ratio model in this study is significantly improved compared with the existing models. The validation dataset had a coefficient of determination (R2) of 0.83, a root mean square error (RMSE) of 3.73 g/L, and a mean absolute percentage error (MAPE) of 44.95% (MAPE is 40.68% at 1–20 g/L, and 12.37% at >20 g/L). On this basis, the UAV also monitored the impacts of heavy rainfall on the CSPM, resulting in a rapid rise and fall in CSPM over a period of ten hours. This study demonstrated the potential of UAV remote sensing for CSPM monitoring in extremely turbid narrow rivers (tens to tens of meters), especially before and after rainfall sediment production events, which can provide technical support for accurate sediment management and source identification in the main tributaries of the Yellow River and help realize the goal of high-quality development of the Yellow River Basin.

Plume dispersal of a hyper-eutrophic micro-estuary to the eastern mediterranean during base flow and flood events

Rivers are the primary source of dissolved and particulate materials entering the oceans. Recent studies conducted in Mediterranean streams showed a decrease in freshwater flow which indicates that this oligotrophic region, and probably other semi-arid oligotrophic regions, are likely to become more affected by small stream discharge and an increase in flood event intensity and frequency which indicates the increasing importance of studying flood conditions. However, little is known about the dispersal patterns of small streams and micro-estuaries and their influence on the coastal environment. We investigated the discharge from the Alexander Stream micro-estuary into the eastern Mediterranean as a case study for the fate of nutrients and pollutants discharged from micro-estuaries. Our objective is to characterize the Alexander Stream plume dispersal during base flow and flood events using salinity as a tracer for solute dispersal and by measuring the concentrations of suspended matter. The advection pattern during base flow was characterized by a current that clings to shore and mostly flows southward as a thin layer. This steady influx enriches the coastal water with high nutrient loads and carries pollutants toward Beit Yannai recreational beach, chronically exposing the shore and its users year-round. During floods, the plume disperses mostly northward along the coastline, and a considerable volume of suspended sediments settles near the estuary outfall, creating a hotspot of potentially contaminated sediment. At the peak discharge of the flood, the high concentrations of suspended sediments form hyperpycnal flows seaward near the seafloor and along the shelf. These results show the influence of small streams on the marine and coastal environments in semi-arid regions, which is predicted to expand to more temperate zones in the future.

Temporal and spatial variation of microplastics in the urban rivers of Harbin

This study was to investigate temporal and spatial variation of microplastics in surface water and sediment in the urban rivers of Harbin during dry and wet season. Water samples (n = 25) in Xinyi River (n = 13) and Ashe River (n = 12) were collected from the selected sampling points. Microplastics in urban rivers in Harbin included polyethylene (PE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The results show that urban rivers in Harbin had relatively mild microplastic abundance with most fragments in shape and colorless in color. PP and PE were the major polymers in surface water samples, while PVC and PET were the major polymers in sediment, which were dominated by large-size and granulate shape microplastics. Source apportionment demonstrate that the main sources of microplastics in Xinyi River and Ashe River during dry season were domestic wastewater and effluent from rainfall, while the main sources of microplastics in Xinyi River and Ashe River during wet season were wastewater, atmospheric sedimentation, and agricultural source. The morphology of microplastics in surface water and sediment in urban rivers of Harbin was negatively correlated with water velocity and positively correlated with the concentration of suspended matter, dissolved oxygen, and conductivity. Riparian vegetation on the sides of Xinyi and Ashe River decreased migration process of microplastics by vegetal purification and then resulted in low abundance of microplastics. In conclusion, this study highlighted the occurrence characteristics, source apportionment and environmental influencing factors of microplastics in urban rivers of Harbin, which may develop new insights into the reduction of abundance of microplastics in the urban rivers.

USE OF THE DYNAMIC LIGHT SCATTERING TO ASSESS THE EFFICIENCY OF SEPARATION OF SUSPENDED AND COLLOIDAL PARTICLES IN RIVER WATERS BY FILTRATION AND CENTRIFUGATION

Link for citation: Shulkin V.M. Use of the dynamic light scattering to assess the efficiency of separation of suspended and colloidal particles in river waters by filtration and centrifugation. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 88-97. In Rus. The relevance of the study is stipulated by the need to control the completeness and accuracy of the separation of suspended and colloidal particles using filtration and centrifugation methods during the analysis of the chemical composition of river waters. The main goal: to test and evaluate the possibility of using the method of dynamic light scattering to monitor the effectiveness of separation of suspended and colloidal particles of river waters by filtration and centrifugation. Objects: waters of typical rivers of the south of the Russian Far East with different levels of anthropogenic load and landscape structure of watersheds, which leads to obvious variations in the concentration levels of dissolved, colloidal and suspended forms of chemical elements in rivers, as well as to different content and grain size composition of suspended matter. Methods: measurement of the dynamic light scattering intensity, including its size distribution, using the Photocor COMPACT Z device in unfiltered samples of river waters, as well as in the filtrates through capsule and membrane filters with varying degrees of clogging, and in the supernatants obtained under various conditions. At the same time, the sum content of suspended and coarse-colloidal particles in the initial samples of river waters was determined gravimetrically after filtration through membrane filters with a pore size of 0,45 μm. Results. The dynamic light scattering intensity in unfiltered river waters demonstrates a significant linear dependence on the suspension content in the range of 5–150 mg/l, determined gravimetrically. In filtrates via a membrane or capsule filter of 0,45 μm, the dynamic light scattering intensity does not depend on the suspension content in the unfiltered samples. Analysis of the size distribution of dynamic light scattering intensity in the unfiltered samples, and in the filtrates confirms the removal efficiency of particles larger than 0,45 μm both at the filtration through membrane or capsule filters, and at the centrifugation for 30' at 4500 rpm. Dynamic light scattering allows characterizing the efficiency of separation of suspended and coarse-colloidal particles in river waters from thin colloids and dissolved forms using membrane and capsule filters, as well as centrifugation. Thus, it becomes possible to control the processes of filters clogging and choose the optimal method for separation of suspended and colloidal particles at the chemical analysis of river waters.

The hyperturbid mesotidal Guadalquivir estuary during an extreme turbidity event: Identifying potential management strategies

The Guadalquivir estuary (SW Iberian Peninsula) is a mesotidal system within a Mediterranean climatic region. It experiences severe and persistent hyperturbid conditions during the wet and cold season, significantly impacting both the ecosystem and various economic activities.During an investigation of an extreme turbidity event, suspended particulate matter (SPM) concentrations exceeding 30 g/L were found near the salt intrusion limit, with a 45 km stretch showing a depth-averaged SPM concentration greater than 10 g/L. Throughout this event, the estuary can accumulate more than 900,000 tonnes of SPM, leading to severe surface light blockage, with the euphotic layer remaining shallower than 10 cm in most areas. Additionally, hypoxia develops in the zone of maximum turbidity, near the bottom.These extreme turbidity events are linked to short-duration freshets that discharge a large amount of sediment from a highly erodible catchment area, followed by a significant reduction in river flow, primarily due to strong water regulation. However, hyperturbid conditions never extend into the summer in this estuary, indicating a non-negligible capacity to clear the SPM.Considering these findings, several recommendations are proposed. First, establishing a monitoring programme for extreme turbidity processes can aid in implementing necessary management actions. Second, it is crucial to develop an optimal protocol for water discharges from the network of dams to maximise sediment export to the sea, minimise plankton washout, and prevent excessive freshwater loss.

Distribution of Hydrocarbons in the Snow Cover of Natural and Urbanized Landscapes in the South of the Far East, Russia.

This study analyzed total organic carbon (TOC), petroleum products (PP), suspended materials (SM), volatile aromatic hydrocarbons (toluene, o-xylene, etc.) and n-alkanes in the snow cover of Bol'shekhekhtsirsky, Zeysky state natural reserves and Khabarovsk, on 4, 5 and 9 stations in the south of the Russian Far East in March 2020. In Bol'shekhekhtsirsky reserve, the concentrations of TOC, PP, and SM in snow samples were in the range of 1.5-2.4, 0.06-0.11, and 11.4-1.9mg/L, 1.4-1.9, 0.02-0.05, and 11-23mg/L in Zeysky reserve, while in Khabarovsk were 1.7-23.7, 0.12-1.26, and 25-294mg/L, respectively. In addition, the benzene, toluene, and o-xylene concentrations of snow samples ranges from not detected (ND) to 2.4, ND-3.1, and 1.1-2.7µg/L in Khabarovsk, ND-1.3, ND-2.1, and ND-2.7µg/L, respectively in Bol'shekhekhtsirsky reserve. Carbon preference index values of n-alkanes were consistent with anthropogenic sources for stations 7, 8 and 2 in Khabarovsk (Heat Power Plants 1, 2 and city roads). The snow of the Zeysky Reserve is not contaminated with organic pollutants, and can be used as a conditional background for the south of the Russian Far East.

Study on the removal of iron (II) and manganese (II) in acidic mine drainage by red mud: Performance and mechanism.

Red mud is an environmental burden during the alumina production process. To mitigate the hazards associated with red mud storage, this study investigated the utilization of alkaline red mud as a treatment agent for acidic mine drainage (AMD) with high concentrations of Fe(II) and Mn(II). This study explored the influence of reaction times, addition amounts of red mud, and pH values on the removal efficiency of Fe (II) and Mn(II) from high-concentration AMD. Various parameters such as suspended solids levels, effluent pH, and zeta potentials were measured to meet discharge standards. The adsorption mechanism of red mud was examined using SEM, XRD, EDX, XPS, and 3D-EEM analysis. Optimal conditions were determined as a reaction time of 2 h, pH value of 5.01 and the addition of 100 g/L red mud, achieving effective removal of Fe(II) (reduced from 1000 to 0.224 mg/L) and Mn (II) (reduced from 20 to 1.03 mg/L). The treated AMD meets discharge standards with reduced suspended matter content of 37.4 mg/L. These findings provided valuable insights for the utilization of red mud waste in engineering applications.

A novel chlorophyll-a retrieval model based on suspended particulate matter classification and different machine learning

Chlorophyll-a (Chla) in inland waters is one of the most significant optical parameters of aquatic ecosystem assessment, and long-term and daily Chla concentration monitoring has the potential to facilitate in early warning of algal blooms. MOD09 products have multiple observation advantages (higher temporal, spatial resolution and signal-to-noise ratio), and play an extremely important role in the remote sensing of water color. For developing a high accuracy machine learning model of remotely estimating Chla concentration in inland waters based on MOD09 products, this study proposed an assumption that the accuracy of Chla concentration retrieval will be improved after classifying water bodies into three groups by suspended particulate matter (SPM) concentration. A total of 10 commonly used machine learning models were compared and evaluated in this study, including random forest regressor (RFR), deep neural networks (DNN), extreme gradient boosting (XGBoost), and convolutional neural network (CNN). Altogether, 41 basic bands and 820 band ratios between the 41 bands were filtered by measuring their correlation with Ln(Chla) and several bands brought into different machine learning models. Results demonstrated that the construction of Chla concentration remote estimation model based on SPM classification could significantly improve the correlation between Ln(Chla) and 41 basic spectral band combinations, the correlation between Ln(Chla) and 820 band ratios, and the model verification R2 from 0.41 to 0.83. Furthermore, B3, B20, and B32 were finally selected based on correlation with SPM to classify SPM and the classification accuracy could reach 0.9. Finally, we concluded that RFR model performed best via comparing the R2, RMSE, and MAPE. By comparing the relative contribution of input bands in different groups, B3 contributed most to three groups. The model constructed in this study has promising prospects for promotion and application in other inland waters, and could provide systematic research reference for subsequent research.

Variations of suspended particulate matter concentrations of the Mackenzie River plume (Beaufort Sea, Arctic Ocean) over the last two decades

This work addresses the last 20 years' evolution of the suspended particulate matter (SPM) concentrations in the Beaufort Sea (Canadian Arctic Ocean) directly influenced by the Mackenzie River discharge. The SPM variations in the coastal zone are highlighted and related to the freshwater and solid discharges of the river measured in situ at the Arctic Red River station (150 km upstream of the river delta). The correlation between the variations of the river discharge and SPM concentration within the surface layer of the coastal waters is obvious. Rather unexpectedly, both have been slightly but significantly decreasing from 2003 to 2018–2019 and started to increase very recently (2019–2022). This change of regime could be explained by changing winter precipitation and groundwater distribution, progressively accumulating sediments within the thawing permafrost layer and its recent release into the groundwater together with thermokarst lakes' rapid drainage.

Численное моделирование последствий дампинга при проведении дноуглубительных работ в прибрежных морских системах

The work is devoted to numerical simulation of the consequences of soil dumping in coastal marine systems. These works are associated with dredging, in which bottom sediments of various types are extracted from the bottom, and then transferred and dumped to a designated discharge site. Soil dumping works lead to the formation of areas with a high concentration of suspended matter (>50 mg/l), the sedimentation of suspended matter and the formation of an additional layer of sediment on the bottom. In the process of mathematical modeling of these processes, it is necessary to consider data on the hydrodynamic characteristics of a water body, the amount and type of soils extracted from the bottom, the redistribution of soils and the concentration of suspended matter in the aquatic environment. This paper presents mathematical models that allow taking into account the diversity of these factors. Based on them, a complex of parallel programs for high-performance computing systems has been developed that allows modeling these processes. The results of work of this complex can be used to assess risks and vulnerabilities in relation to soil dumping, as well as the implementation of environmental design in relation to a specific water body.

In situ correlation between microplastic and suspended particulate matter concentrations in river-estuary systems support proxies for satellite-derived estimates of microplastic flux

Rivers are key pathways for transporting microplastics from land to the oceans, yet microplastic flux estimates remain uncertain. Remote sensing allows repeated broad-scale measurements and can be used to extrapolate limited in situ observations. This study investigated the relationship between suspended particulate matter (SPM), a satellite-observable water quality parameter, and microplastic concentration in a partially mixed estuary (Tamar, UK). Microplastic concentrations ranged from 0.04 to 0.99 microplastics/m3, decreasing downstream. A significant correlation was found between SPM and microplastic concentration over two seasons. This relationship was used to compute a multiyear timeseries of proxy microplastic concentration from satellite imagery and produce estimates of annual proxy microplastic flux. This approach could be applied to investigate microplastic flux in other major rivers worldwide where such a relationship between microplastics and SPM exists. To apply this workflow elsewhere, the establishment of local SPM-to-microplastic relationships from in situ observations and local validation of remote sensing SPM algorithms are essential.

Твердый сток реки Дон и поступление взвеси в дельту при нагонах: статистическое моделирование и сопоставление в период маловодья

Statistical modeling of the Don River solid runoff based on water discharge and turbidity measurements obtained at the hydrological station in the village of Razdorskaya for the twelve-year period 2009–2020 was carried out. The WRTDS (Weighted Regressions on Time, Discharge, and Season) and WRTDSKalman (WRTDS with Kalman filtering) methods were applied. The developed statistical model is aimed at solving the problem of the imbalance between the regularity of collecting data on water discharge and data on the concentration of suspended matter by “restoring” the concentration values on days without measurements based on data on the most “similar” days with measurements in terms of time, discharge and season and does not claim to describe a relationship between the concentration of the constituent of interest and discharge. The quality of the developed statistical model and its modification were checked. The average daily concentrations and fluxes of suspended matter were compared with estimates of the volumes of suspended material deposited during periods of recurring strong surge phenomena. A comparative assessment of sea and river factors contributions to the transport and sedimentation of suspended matter in the Don River delta was fulfilled.

Spreading of the Amazon River Plume

Results of a joint Russian-Brazilian expedition to study the dynamics of continental river runoff in the ocean associated with the Amazon plume are presented. The stations of the study region covered the seaward part of the Amazon plume. The work was carried out in the dry season (November). The data of in situ measurements and satellite data show that the most desalinated and rich in suspended particulate matter and chlorophyll-a waters were localized on the shallow inner shelf. The horizontal and vertical structure of the thermohaline fields indicates the presence of a well-pronounced river plume about 15 m thick. The decrease in salinity in the plume relative to the background values exceeded 6 PSU even at 300–400 km from the river mouth. The plume waters were characterized by increased concentrations of suspended matter. The best approximation to the in situ measurements is provided by the SMOS satellite salinity data and reanalysis GLORYS12. Chemical determinations in the surface layer in the area of the plume reveal elevated concentrations of silicates, phosphates, and nitrites compared to the seaward part.

The control of particulate matter and hydrogeochemistry on uranium–thorium partition coefficients in two representative lakes, Qaidam Basin, China

Radionuclides (including those of uranium and thorium) are commonly used to quantify complex geochemical processes in aqueous environments. The estimation of mass transport fluxes for uranium (U) and thorium (Th) isotopes is plagued, however, by uncertainties predominantly driven by the inability to determine solute–particulate partition coefficients (Kd). Such uncertainties are especially pronounced for lakes in rarely studied, environmentally sensitive areas. This study examines the factors controlling the Kd values of U and Th isotopes in both freshwater (Keluke Lake) and saline water (Tuosu Lake) lakes within the Qaidam Basin, China, a basin sensitive to the impacts of climatic change. The analysis found a negative correlation of both Kd(Th) and Kd(U) with the concentration of suspended particulate matter (SPM), suggesting that particle concentrations affect Kd values in the sandy Keluke Lake. In contrast, there was no significant correlation between Kd values and SPM in the muddy (fine-grained) Tuosu Lake. Compositionally, three types of particles were found in both lakes and were derived from the same sediment sources. The Kd values were primarily controlled by lake evaporation and/or secondary water–rock interactions that were influenced by hydrogeochemical ecosystem differences between the lakes. In addition to differences in particle composition and concentrations, redox potential, ionic strength, organic matter concentration and pH of the lake water were likely to influence the Kd(Th) and Kd(U) values. These results are not only of significance to quantitative studies of U and Th isotopes in water (e.g., reducing transport flux uncertainties and improving the precision of U–Th isotope dating), but also provide an important reference for the application of radionuclides in other climate sensitive regions of the world.

Assessment of Suspended Particulate Matter (SPM) and Toxicity Potential (TP) of Emissions from Different Power Generating Sets in Ado-Ekiti, Nigeria

This research investigated the levels of Suspended Particulate Matter (SPM) resulting from the emissions of various power generators in Nigeria. Additionally, the study conducted risk assessments concerning the inhalation of this pollutant from different power generators, and proposed suitable measures to control the emission of SPM linked to the use of power generators. To capture the exhaust from each generator set, a sampling technique was employed. This involved using a sample probe, a filter, and a filter holder to trap the gas emissions in a sequential manner. The concentration of SPM in the air was calculated based on several factors, including the weight difference of the filter paper before and after sampling, the sampling duration, and the flow rate. The concentration of suspended particulate matter for the 16 different generating sets varied from 1413.4 µg/m3 to 5300 µg/m3, with an average concentration of 2912.98 µg/m3. These values surpassed both the World Health Organization (WHO) standard of 50 µg/m3 and the Nigeria Ambient Air Quality Standard of 250 µg/m3. The study's findings indicate that power generating sets emit Suspended Particulate Matter (SPM) through their gas exhaust. Moreover, the results demonstrate that the generator samples lacking a galvanized mesh at the gas stream exhaust exhibit significantly higher toxicity potential compared to those with the galvanized mesh. This research established that SPM concentrations were found from the exhaust of different power generating sets.

Assessment of the Environmental Impact of Discharges from Fishmeal Factories Located in Levrier Bay, Nouadhibou-Mauritania

Levrier Bay, located in the western part of Mauritanian Cost, has a strategic position in Mauritania’s fish economy and reproduction environment. Recently, fishmeal factories have multiplied in the bay. This study was carried out in Levrier Bay. It is the first one in this area which is interested in assessing the environmental impact of fishmeal factory discharges by measuring several parameters such as suspended matter, chemical oxygen demand (COD), biological oxygen demand (BOD), conductivity, turbidity, and salinity. A total of 27 samples were collected at 9 sites distributed on the link between effluents from factories and the Atlantic Ocean (discharge site). Results show that some parameters are over permissible values, like suspended matter content (SS), which reached 2020 mg. L.-1 level. The turbidity measure shows excessively high values (50 to 961 mg.L.-1); impacted by effluents at the reject point, the seawater conductivity and salinity are particularly low (4.53 to 188.2 and 13 to 56.4, respectively). The total organic carbon (TOC) values ranged from 200 to 780 mg/L, whereas the highest measured level of chemical oxygen demand was 4010 mg.L.-1 Biochemical oxygen demand content ranged from 685 to 961 mg/L. The biodegradability index (COD/BOD) shows that these effluents are not easily biodegradable because the index > 3.